The infection
Hepatitis B is caused by a virus that infects the liver. It is extremely infectious: the amount of virus in blood can be hundreds of times higher than for HIV, and a minute quantity of blood is enough. Worldwide, transmission from mother to child at birth and infection in early childhood remain dominant; in countries with high vaccine coverage, sexual and blood-borne transmission predominate.
Key facts
| Organism | Hepatitis B virus, a DNA virus |
|---|---|
| Incubation | Six weeks to six months |
| Infectiousness | Very high, well above HIV |
| Testing from | Surface antigen usually detectable from four to six weeks |
| Becomes chronic | About 5% of adults, up to 90% of infected newborns |
| Curable | Usually clears spontaneously in adults; chronic infection is controlled, not cured |
| Vaccine | Yes, highly effective, three doses |
How it is transmitted
The virus passes through blood, unprotected sex, and from mother to child at delivery. Sharing injecting equipment, poorly sterilised tattoo or piercing equipment, and even sharing a razor or toothbrush can be enough. The virus survives for days on surfaces, which explains transmission through contaminated objects.
Symptoms
Acute infection goes unnoticed in most cases. When symptomatic it produces marked fatigue, nausea, abdominal pain, dark urine and jaundice, weeks to months after exposure. Chronic hepatitis is silent for years, sometimes decades, and declares itself only at the stage of complications — which is why it is so often found by accident.
Testing
Testing rests on three blood markers read together: surface antigen, which indicates current infection; core antibody, which records past or present contact with the virus; and surface antibody, which indicates protection, whether from vaccination or from recovery. It is the combination that shows whether a person is infected, recovered, vaccinated or susceptible. Screening is routine in pregnancy.
Treatment
Acute hepatitis is usually not treated: it clears spontaneously in more than nine out of ten adults. Chronic hepatitis is treated with antivirals, tenofovir or entecavir, which suppress viral replication, prevent cirrhosis and reduce liver cancer risk — but do not eliminate the virus and are often lifelong. Regular liver monitoring is needed even without treatment.
If left untreated
Chronic infection progresses to fibrosis and then cirrhosis, and carries a risk of hepatocellular carcinoma, which can occur even without cirrhosis. That risk justifies regular ultrasound surveillance in chronic carriers. A newborn infected at birth becomes a chronic carrier in the great majority of cases, which is why antenatal screening matters so much.
Prevention
- Vaccination is the single most effective measure: three doses give lasting, usually lifelong, protection.
- It is part of routine infant immunisation in most countries and compulsory in several.
- Condoms protect during sex; do not share razors, toothbrushes or injecting equipment.
- After exposure, vaccine plus immunoglobulin, as soon as possible and within 72 hours at the latest, prevents infection.
After a diagnosis
- Have close contacts and partners tested and vaccinated: that is the most useful single step.
- With chronic infection, regular liver monitoring is required even without symptoms or treatment.
- Tell any clinician before an invasive procedure.
- Pregnancy in a carrier requires treatment of the newborn from birth, which is highly effective.
Worth remembering
A vaccine given in childhood usually protects for life without boosters. If you are unsure of your status, a simple antibody test will tell you whether you are protected.
A little history
Epidemic jaundice has been known since antiquity, but the idea that jaundice could be transmitted by blood was born in Bremen in 1883: after a smallpox vaccination campaign using human lymph, nearly 200 shipyard workers developed hepatitis, which the physician Lürman reported in 1885. In 1942 tens of thousands of American soldiers vaccinated against yellow fever with a vaccine stabilised with human serum fell ill: "serum hepatitis" was from then on distinguished from "epidemic" hepatitis (hepatitis A).
The virus was approached by chance. In 1965 Baruch Blumberg, studying blood proteins in populations around the world, found in the serum of an Australian Aboriginal man an unknown antigen he called the "Australia antigen": it was the envelope of the hepatitis B virus. The complete particle was photographed by David Dane in 1970. Blumberg received the Nobel Prize in 1976, and systematic screening of blood donations cut transfusion transmission.
The first vaccine, made from the plasma of chronic carriers, was approved in 1981; the recombinant vaccine, produced by genetically modified yeast, replaced it from 1986 — through the liver cancer it prevents, it is the first anti-cancer vaccine. The WHO has recommended vaccinating all infants since 1992. Antivirals (lamivudine 1998, tenofovir 2008) control chronic infection without yet curing it.
Country by country
The medicine is the same everywhere, but access, prevention programmes, what is free of charge and which services are responsible differ completely. Each country below has its own page.
Select a country to open its detailed page.
